1. Field of the Invention
The present invention relates in general to an intermittently operated transmitter which radiates high transmission power and is intermittently driven.
2. Description of the Prior Art
The signal transmission system for transmitting a signal through a satellite, for example, is known comprising a signal transmission system having short duration and high transmission power in which a frequency of 1.6 GHz is used and data is transmitted during a 100 ms period with a transmission of 40 W.
A satellite communication transmitter is known wherein a power amplifying stage or circuit connected to an antenna operates in class "C" mode so as to obtain high power efficiency and has a power supply having a large capacity and in which a voltage as, for example, 30 volts and a current of about 5 amperes is required to drive the power amplifying circuit. See U.S. Pat. No. 4,509,199. In general, with such conventional transmitter when it is driven, a power source voltage supplied to the transmitter is boosted by using a DC-DC converter having a large capacity and a power of 30 volts and 5 amperes which in the above-mentioned example is directly supplied to the power amplifying circuit.
Thus, in the prior art transmitter, described above, the power supply having a large capacity with about 30 volts and 5 amperes is required to drive the power amplifying circuit. Also, a DC-DC converter having a large capacity is required when the power amplifier circuit is driven by the battery.
It may be considered to use a DC-DC converter having a small capacity to charge a capacitor from the battery so as to drive the amplifying circuit, but such drive method has the following defects. When the power amplifying circuit is directly driven by the voltage stored in the capacitor, the voltage drops very rapidly upon operation of the transmitter so that the output power of the power amplifying circuit is difficult to maintain and the power efficiency is low.